Safety interlock



Feb. 15, 1966 .1. F. PROBST SAFETY INTERLOCK 5 Sheets-Sheet 1 Filed July 24, 1963 Feb. 15, 1966 J. F. PROBST 3,234,827

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" wxWg 29 Feb. 15, 1966 J. F. PROBST SAFETY INTERLOCK 5 Sheets-Sheet 5 Filed July 24, 1963 United States Patent 3,234,827 SAFETY INTERLOCK John F. Probst, South Bend, Ind, assiguor to Amsted Industries Incorporated, Chicago, 111., a corporation of New Jersey Filed July 24, 1963, Ser. No. 297,292 7 Claims. (Cl. 82-22) This invention relates to machine tools and more particularly to safety interlock arrangements which permit one gear actuating mechanism of a lathe apron to operate and at the same time prevent the operation of another lathe apron gear actuating mechanism.

The conventional lathe apron and carrying assembly at times employs two means of transferring motion from the gear box to the assembly so that the work tools mounted on the cross slide may be selectively moved to accomplish a desired machining operation. The primary means utilizes an hexagonal rotating feed rod extending the length of the lathe and rotated by internal gear mechanism located within the gear box. A first clutch arrangement located on the apron is releasably engageable with the feed rod and is effective to move the apron and carriage assembly along the bed of the lathe. The secondary means utilizes a threaded lead screw extending the length of the lathe and rotated by other internal gear mechanism located within the gear box. A second clutch arrangement located on the apron is releasably engageable with the lead screw and is effective to move the apron and carriage assembly along the bed of the lathe.

Obviously, it is necessary that the feed rod clutch be prevented from transferring motion to the apron from the feed rod when the lead screw clutch is engaged with the lead screw. Conversely, it is necessary to prevent the lead screw clutch from engaging the lead screw when the feed rod clutch is transferring motion from the feed rod.

It is therefore necessary to provide a safety interlock arrangement in order to prevent engagement of the feed rod clutch while the lead screw clutch is engaged and to prevent engagement of the lead screw clutch while the feed rod is engaged.

In the past it has been common practice to employ various cam and lover arrangements to accomplish this purpose. However, such attempts have failed to provide a satisfactory solution to the problem and have been slow acting, undependable and generally expensive to maintain.

Accordingly, it is an object of this invention to provide interconnected mechanism that alternately and optionally prevent operation of one power transfer arrangement while simultaneously permitting operation of another power transfer arrangement.

An additional object of this invention is to provide mechanism that will prevent engagement of a feed rod clutch with a pinion driving gear when a lead screw clutch is engaged with a lead screw.

A further object of this invention is to provide mechanism that will prevent engagement of a lead screw clutch with a lead screw when a feed rod clutch is engaged with a pinion driving gear.

A still further object of this invention is to provide a safety interlock arrangement that positively prevents a feed selector gear from engaging optionally selected driven gears while a lead screw clutch is engaged with a lead screw.

An additional object of this invention is to provide a safety interlock arrangement that positively prevents a lead screw clutch from engaging a lead screw while a feed selector gear is engaged with an optionally selected driven gear.

A further object of this invention is to provide a safety interlock arrangement that simultaneously prevents a feed rod clutch from engaging a pinion driving gear and a feed gear from engaging optionally selected driven gears while a lead screw clutch is engaged with a lead screw.

An additional object of this invention is to provide a safety interlock arrangement that simultaneously prevents a lead screw clutch from engaging a lead screw while a feed rod clutch is engaged with a pinion driving gear and a feed gear is engaged with an optionally selected driven gear.

Other objects and advantages of this invention will become apparent when reference is made to the following written description considered in conjunction with the accompanying drawings wherein:

FIGURE 1 is a fragmentary perspective view of a lathe showing the lead screw and feed rod extending from the gear box to the tail end, and with an apron and carriage assembly positioned on the bed;

FIGURE 2 is a fragmentary, partly sectional front view of the apron, showing portions of the interlock mechanism;

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 2 showing the operating shaft that receives motion from the feed rod and in turn transfers motion to other internal mechanism of the apron;

FIGURE 4 is a top plan view of the lathe apron with its cover removed showing the relative positions of the feed selector gear and the half nut cam shaft assembly;

FIGURE 5 is a combined sectional view taken along lines 5-5 and 55 of FIGURE 2 showing the feed reverse shaft and feed selector gear locked in non-operable positions, and the half nut cam shaft in operable position;

FIGURE 6 is essentially the same view as FIGURE 5, but showing the feed reverse shaft and feed selector gear in operable positions, and the half nut cam shaft in nonoperable position;

FIGURE 7 is a side elevational view of the apron, partly in section, showing the half nut cam and half nut interlock disk assembled on the half nut cam shaft;

FIGURE 8 is an elevational view of the back of the apron illustrating the half nut clutch means for engaging the lead screw and the feed reverse clutch yoke for transferring motion from the feed rod to a pinion driving gear;

FIGURE 9 is a view taken along line 99 of FIG- URE 3 showing circumferential detail of the feed interlock disk;

FIGURE 10 is a view taken along 10-10 of FIGURE 7 showing circumferential detail of the half nut cam; and

FIGURE 11 is a view taken along line 11--11 of FIG- URE 7 showing circumferential detail of the half nut interlock disk.

Referring to FIGURE 1, a lead screw 11 is journaled at one end in a gear box 12 secured near the head end of a lathe indicated generally at 10. The lead screw seletively receives rotative motion from an internal power source (not shown) through a conventional geared arrangement located within the gear box. The other end of the lead screw is journaled in a support bracket 13 secured near the tail end of the lathe. A feed rod 14 is journaled at one of its ends in the gear box 12 and selectively receives rotative motion from said internal power source through another conventional geared arrangement located within the gear box. The other end of the feed rod is journaled in a lower portion of the support bracket 13.

A carriage 15 is supported in slideable contact by a bed 16 of the lathe. An apron 17 depends from the carriage and is disposed to move therewith. The apron has located thereon two clutch arrangements, hereinafter described, one for selectively engaging a feed rod pinion driving gear, the other for selectively engaging the lead screw. Whenever the feed rod or lead screw is engaged by its respective clutch arrangement, motion may be transferred to the apron and carriage to move this assembly longitudinally of the lathe along the ways of the bed.

Referring to FIGURE 3, an operating shaft has its inner end extending through an opening of a back wall 23 of the apron 17. The outer end of the shaft 20 is journaled in slideable and rotatable contact within a bore 24 formed through a generally cylindrical retainer collar 26 that threadably engages an opening of an extension 28 of a front wall 29 of the apron. A generally cylindrical spanner nut 30 is located about and threadably engages the outer periphery of the retainer collar 26 and when tightened against the front surface of the extension 28 serves to secure the retainer collar 26 in the front wall 29 of the apron.

A circumferential slot 32 is formed on a portion of the operating shaft 20 located within the bore 24 of the retainer collar 26. A radially expandable O ring 33 is mounted in the slot 32 and expands against the bore 24 of the retainer collar 26. The O ring serves as an oil seal between shaft 20 and retainer collar 26. A feed reverse lever 34 is located about the outer end of the operating shaft 20 and is secured thereto as by a set screw 35 engaging a keyway 21 formed in the operating shaft.

The feed reverse lever 34 is thereby effective to rotate the operating shaft 20.

An assembly comprising an operating gear 36 has secured within its bore a plurality of internal bushings 36a and is located about the operating shaft 20 in rotatable and slideable contact therewith. The operating gear 36 is positioned on the operating shaft 20 so that an inner end of the operating gear abuts an outer surface of a generally cylindrical shoulder 38 having a diameter substantially larger than the nominal diameter of the operating shaft. A washer 39 having an inner diameter substantially larger than the outer diameter of the operating gear is located about an outer non-toothed portion of the operating gear and serves as an oil slinger during rotation of the operating gear.

A generally cylindrical feed reverse interlock disk 40 is located about and positioned on the operating shaft 20 in abutting contact with an outer end of the operating gear 36 and with an inner end of the retainer collar 26. The disk 40 is secured to the operating shaft 20 as by a key 40a so that the disk rotates as a unit with the operating shaft.

A generally cylindrical sleeve bearing 42 is located about an outer diameter of an extension 44 of a bevel gear 46 in slidable and rotatable Contact therewith. A small steel ball 42a is located with the outer circumferential surface of the sleeve bearing 42 and the inner circumferential surface of the opening formed through the back wall 23 of the apron. The small steel ball 42a is effective to hold the sleeve bearing 42 stationary in the back wall opening so that the extension 44 of the bevel gear may rotate within the sleeve bearing 42. The bevel gear 46 has its extension 44 located about an inner non-toothed portion of the operating gear 36 and is secured thereto as by a key 22 so that the bevel gear 46 and the operating gear 36 may rotate as a unit about operating shaft 20. The bevel gear 46 has an inner bore somewhat larger than the diameter of shoulder 38 of operating shaft 20.

The operating shaft 2t) has a generally cylindrical extension 48 engageable with feed rod clutch mechanism in a manner hereinafter described and is effective to cause feed rod 14 to selectively engage bevel gear 46 through an intermediary gear arrangement hereinafter described.

A generally cylindrical selector gear shaft 56 is journaled in rotatable and slideable contact with a shift rack housing 51 secured to an upper portion of the front wall. 29 of the apron 17. The selector gear shaft has secured at its outer end, as by a conventional expandable screw arrangement 50a, a shift rack 52 having a plurality of grooves formed thereon. A rack pinion gear 54 has a plurality of teeth engaged with some of the grooves of the shift rack 52 so that rotation of the pinion gear 54 causes shift rack 52 and selector gear shaft 50 to move as a unit in an axial direction.

The shift rack 52 has formed at its outer end a plurality of abutment members 52a that are formed to receive a plurality of segments 56 urged radially inwardly by a radially expandable O ring 58. The O ring 58 and segments 56 in conjunction with one or more of the abut ment members 52a serve to maintain the selector shaft 59 in a desired axial position. A feed lever 59 (as best seen in FIGURE 2) is secured to an outer end of the rack pinion gear 54 and is effective to rotate the rack pinion gear 54 and thereby move the selector gear shaft 5% in an axial direction.

A feed selector gear 60 is secured to the inner end of the selector gear shaft 50 as by a key 60a. The feed gear 60 has a plurality of circumferential teeth engaged with a plurality of circumferential teeth of the operating gear 36 and is disposed to be rotated as determined by rotation of the operating gear 36. The feed gear 6! when moved axially by clockwise or counterclockwise rotation of the feed selector lever 59 engages either a longitudinal feed clutch 62 or a cross feed gear 64. Feed selector gear 60, after engagement with either the feed clutch 62 or cross feed gear 64, may be rotated as directed by the operating gear 36 and thereby causes motion to be transferred to either the feed clutch 62 or the cross feed gear 64. The feed clutch is connected to conventional longitudinal feed gear mechaninsm and the cross feed gear is connected to conventional cross feed gear mechanism. Therefore, motion from either the feed clutch or the cross feed gear is employed to provide either longitudinal movement to the apron and carriage assembly, or cross feed movement to the cross slide.

Again referring to FIGURE 3, a countersunk, substantially vertical aperture 43 is formed through a bottom wall 17a of the apron and is generally aligned with the feed disk 40. An upper portion 45 of said aperture slideably receives a steel ball 47. A coil spring 49 is located within the upper portion 45 of the aperture with one end abutting the steel ball 47. A hollow-headed set screw 53 is threadably received in a lower portion 55 of the aperture. The set screw has an inner end in abutting contact with the other end of the coil spring 49 and maintains the coil spring compressed against the steel ball 47 that in turn is urged against the circumferential surface of the feed disk 40. A jam nut 53a threadably engages set screw 53 and when urged against a boss of bottom Wall 1711 of the apron serves to maintain the set screw in any desired position within the lower portion 55 of aperture 43.

The steel ball 47 partially projects from the upper portion of the aperture 43 when urged against the circumferential surface of the feed disk 40 and is disposed to be received by any one of a plurality of truncated notches 40b, 4010, 44911, as best seen in FIGURE 9. The disk 40 also has a notch 41 formed in its circumferential surface for a purpose to be hereinafter described. The steel ball 47, whenever engaged with one of the truncated notches, serves to releasably hold the operating shaft 20 in a position so that the operating gear, as will be described, may transfer either forward or reverse motion to cooperating gear arrangements or the operating gear may be held in neutral position with no motion being transferred to cooperating gear arrangements.

As best seen in FIGURE 8, the bevel gear 46 has a plurality of teeth 66 that simultaneously engage teeth 67 of one pinion bevel gear 68 and teeth 69 of another pinion bevel gear 70. Pinion gears 68 and 70 are journaled in general alignment with each other in oppositely disposed walls 71 and 71a, respectively, of an extension of the back apron wall 23.

Each pinion gear 68 and 70 is disposed about the feed rod and has an inner diameter somewhat larger than the width across corners of the feed rod to allow relative freedom of rotation therebetween.

A feed reverse clutch 72 is internally formed to be complementary to the hexagonally shaped feed rod 14 and when located about said feed rod is disposed to rotate as a unit therewith. The clutch 72 is comprised of teeth 73 at times engageable with teeth 74 of the pinion bevel gear 68 and teeth 75 at other times engageable with teeth 76 of the other pinion bevel gear 70. The clutch is also comprised of two ridge-like portions 77, 77a, .ad jacent to its toothed ends and has a generally cylindrical portion 78 formed intermediate the ends of the clutch between the ridge-like portions. A generally U shaped feed reverse clutch yoke 80 is located about the cylindrical portion 78 of the clutch in loosely rotational contact therebetween and also in abutting contact with ridges 77 and 77a.

The generally cylindrical extension 48 (FIGURE 3) has a smaller diameter than the diameter of the operating shaft 20 and is formed eccentrically on the inner end thereof. The extension 48 is received by an opening 81 formed in the clutch yoke 80. Rotation of feed reverse lever 34 causes the operating shaft 20 to rotate and the extension 48 is thereby caused to move angularly, as a crank, about the axis of the operating shaft 20. This movement in turn causes the yoke 80 to move axially of rod 14 against ridge 77a to move the feed clutch linearly so that teeth 73 are disengaged from teeth 74 of the pinion bevel gear 68 and teeth 75 become engaged with teeth 76 of the other pinion bevel gear 70, with a midpoint whereby the feed clutch 72 is disengaged from both pinion bevel gears 68 and 70. In this manner, unidirectional angular motion of the feed rod may be transferred into bidirectional rotation of the operating gear, or the feed rod may rotate without transferring any motion to the operating gear.

Now referring to FIGURE 7, a half nut cam shaft 90 is journaled near its outer end in the front wall of the apron and extends through an opening 91 of the back apron wall. A generally cylindrical half nut interlock disk 92 is located about the cam shaft 90 and is secured thereto as by a spring pin 92a. As best seen in FIGURE ll, the half nut disk 92 has at least one obtusely angled, triangularly shaped notch 93 formed in its circumferential surface.

Again referring to FIGURE 7, a half nut cam 94 is located about the cam shaft 90 and is secured thereto as by a spring pin 94a. As best seen in FIGURE 10, a generally triangularly shaped, obtusely angled notch 95 is formed in the circumferential surface of the half nut cam 94. The half nut cam has a portion of its circumferential surface received in slideable and rotatable contact by the opening formed in a portion of the back apron wall and thereby serves to journal the inner end of the cam shaft 90 in the back apron wall. A plurality of generally rectangular grooves 96, 96 are formed in a surface 97 of the half nut cam 94 and receive one end of a like plurality of half nut pins 98, 98 in slideable contact therebetween. The other ends of the half nut pins are received in recesses 99, 99 formed in half nuts 100, 100slideably confined in a vertical guide 101 formed rearwardly of the back apron wall (see also FIGURE 4).

A half nut lever 102 is located about the outer end of the cam shaft 90 and is secured thereto as by a taper pin 102a. counterclockwise rotation of the lever 102 causes cam shaft 90 to rotate and is effective to move half nut disk 92 and half nut cam 94, secured to the cam shaft 90, in an angular direction. This rotation of the half nut cam causes the half nut pins to slide in their respective grooves and the resultant effect is that half nuts 100, 100 are urged inwardly toward each other. As said half nuts 100, 100 are continued to be urged toward each other, internal threads 102, 102 formed in the half nuts engage complementary threads 103 formed on the lead screw 11. In this manner, motion of the lead screw 6 may be transferred into rectilinear motion whereby the apron and carriage are caused to move longitudinally along the bed of the lathe.

A generally cylindrical projection 104 is formed concentrically on the inner end of the half nut cam shaft and when the half nuts are closed upon the lead screw, the projection engages recesses 105, 105 formed in the half nuts and thereby prevents excessive inward travel of the half nuts and ensures proper engagement of the half nut threads 102, 102 with the threads 103 of the lead screw.

It may be seen that clockwise rotation of handle 102 is effective to urge the half nuts 100, .100 outwardly from each other, disengaging the threads of the half nuts from the threads of the lead screw and thereby preventing movement of the apron and carriage along the bed of the lathe.

As best viewed in FIGURES 5 and 6, a generally cylindrical portion 111 of a feed reverse interloc plunger is slideably received by an opening formed through a feed selector interlock housing 112 positioned between the front and back apron walls. The location of the housing 112 is selectively determined by an extension113 being received in an opening in the back apron wall, and a set screw 114 extending through the front apron wall and threadably received by the interlock housing 112. The interlock housing 112 is secured in a. substantially vertical position between the front and back apron walls by a :plurality of set screws 115, 115 (FIGURE 2), threa-dably extending through apron front Wall openings and urged against inner surfaces of recesses 116, 116 (FIGURE 4) for-med in the interlock housing 112.

The interlock housing 112 is disposed between the front and back apron walls so that a forked end portion 117 of the interlock plunger 110 may at times straddle and thereby restrain the feed selector gear 60 from any movement in its axial direction. An interlock spring 118 is located about the cylindrical portion 111 of the interlock plunger 110 so that one end abut-s one side of the interlock houisng 112. The other end of the interlock spring 118 is secured near the end 119 of cylindrical portion 111 as by a retaining ring 120. The interlock spring 118 is effective to continually urge the interlock plunger forked end portion 117 out of straddling engagement with the feed selector gear 60 and, when the lever 102 is in the open position, simultaneously urge the plunger end 119 into the notch 95 formed in the circumferential surface of the half nut cam 94.

A reverse interlock pin 122 is slideably received by openings formed through interlock bushings 123, 123 secured to the inner surface of the front apron wall as by screws 124, 124. The openings of the bushings have their axes generally coaxially aligned between the operating shaft 20 and the half nut cam shaft 90. The interlock pin 122 is thereby disposed between the circumferential surfaces of the feed reverse interlock disk 40 and the half nut disk 92. Thus, when shaft 50 is in neutral position, rotation of camshaft 90 by lever 102 will cause pin 122 to be urged out of notch 93 of half nut disk 92 into engagement with the obtusely angled triangular notch 41 in the circumferential surface of interlock disk 40 and thereby prevent rotation of the operating shaft 20.

It shall be noted that one end of interlock pin 122 will engage notch 41 of the interlock disk 40 only when operating shaft 20 has been rotated to a neutral position at which time the extension 48 (FIGURE 8) of shaft 20 will maintain feed clutch 72 in a neutral position whereby neither teeth 73 nor teeth 75 of the feed clutch engage teeth 74 or teeth 76 of pinion bevel gears 68, 70, respectively.

It shall be noted further that when one end of inter lock pin 122 engages notch 41 of the interlock disk 40, the other end of the pin will not be received by the notch 93 formed in the circumferential surface of the 7 half disk 92. Thus, half nut disk 92 and half nut cam 94 secured to the cam shaft 90 are free to rotate as directed by lever 102, and half nuts 100, 1% may be closed about lead screw 11.

Furthermore, as half nut cam shaft 96 is rotated as explained heretofore, interlock plunger 11th is urged out of engagement with notch 95 of half nut cam 94 and the forked end portion 117 of the interlock plunger is moved into straddling engagement with the feed selector gear 60.

Therefore, when the half nuts are closed about the lead screw and motion is being transferred from the power source through the lead screw to the apron and carriage, operating shaft is maintained in a neutral position by engagement of interlock pin 122 with notch 41 of interlock disk and no motion will be trans ferred from the feed rod to the apron and carriage. Also, at the same time, feed selector gear is maintained in a neutral position by having forked end portion 117 of interlock plunger 110 in straddling engagement with the feed gear 60.

Thus, whenever the lead screw is transferring motion to the apron and carriage, handles 34 and 59 are prevented from operating the shaft 20 and feed gear 60, respectively.

When handle 102 is rotated to the open position, the half nuts no longer engage the lead screw, and notch 95 of half nut cam 94 is in position to receive the end 119 of interlock plunger 110 which is being urged out of engagement with feed gear 60 by the interlock spring 118. Also, 'half nut disk 2 has been rotated so that its notch 93 is axially aligned with interlock pin 122. Rotation of handle 34 of the operating shaft will cause feed disk 40 to rotate, and interlock pin 122 is urged out of engagement with notch 41 of the feed disk. As interlock pin 122 is urged out of engagement with notch 41, it moves upwardly into engagement with notch 93 of the half nut disk 92, thereby preventing rotation of the half nut cam shaft 90. Interlock pin 122 is maintained in engagement with notch 93 of half nut disk 92 so long as one end remains in contact with the circumferential surface of the feed disk 40.

Feed selector gear 60 no longer being restrained by interlock plunger 110, is free to be axially moved by rotation of handle 59 into engagement with either longi tudinal feed gear 62 or cross feed gear 64, (FIGURE 3).

Also, operating shaft 20 is free to rotate as directed by handle 34, and extension 48 of the operating shaft may move feed clutch 72 into engagement with either pinion gear 68 or pinion gear 70 thus imparting clockwise or counterclockwise motion to operating gear 36 and subsequently causing selective forward or reverse motion to be imparted to the tools secured on the carriage.

Therefore, when feed clutch 72 is engaged with either pinion gear 68 or pinion gear 70 and motion is being transferred from the power source through the feed rod to the apron and carriage, the half nut cam shaft is prevented from rotation by the interlock pin 122 being engaged with the notch 93 of the half nut disk 92 and the half nuts 10%), remain in an open position about the lead screw :so that no motion will be transferred from the lead screw to the apron and carriage. Also, at the same time, interlock spring 119 urges and maintains interlock plunger in engagement with notch 95 of half nut cam 94 so that feed gear 60 may rotate as directed by operating gear 36.

Although but one embodiment of the invention is disclosed and described herein, it is apparent that other embodiments and modifications are possible within the scope of the appended claims.

I claim:

1. In a lathe including a longitudinal bed, powerdriven means extending the length of said bed, and a carriage slideably supported on said bed and having an Cit apron including mechanism for drivingly engaging said power-driven means with said carriage; said apron mechanism comprising first and second clutch means for effectuating the driving engagement, said first and second clutch means being controlled by the rotation of operating and cam shafts, respectively, pin means for selectively maintaining one of said shafts operable while the other one of said shafts is non-operable, a cam rotatable with said cam shaft and having a notch formed in its periphery, a rotatably-mounted selector gear axially movable between cooperating gear means, a plunger reciprocally movable between said selector gear and cam, said plunger having a first end portion receivable at times in said notch and a forked, second end portion straddling said selector gear when said first portion is not received in said notch, and yieldable means biasing said plunger out of straddling engagement with said selector gear, saidplunger being movable by rotation of said cam shaft to straddle said selector feed gear with said forked portion to prevent rotation of said operating shaft.

2. In a lathe including a longitudinal bed, powerdriven means extending the length of said bed, and a carriage slideably supported on said bed and having an apron including mechanism for drivingly engaging said powerdriven means with said carriage; said apron mechanism comprising first and second clutch means for etfectuating the driving engagement, said first and second clutch means being controlled by the rotation of operating and cam shafts, respectively, first and second cams rotatable with said cam shaft, an interlock disk rotatable with said operating shaft, each of said cams and interlock disk having a notch formed in its periphery, a pin reciprocally movable between said first cam and interlock disk, said pin having a first end portion receivable at times in said first cam notch and a second end portion receivable in said interlock disk notch when said first end portion is not received in said first cam notch, a rotatably-mounted selector gear axially movable between cooperating gear means, a plunger reciprocally movable between said selector gear and second cam, said plunger having a first end portion receivable at times in said second cam notch and a forked, second end portion straddling said selector gear when the first end portion of said plunger is not received in said second cam notch, and yieldable means biasing said plunger out of straddling engagement with said selector gear, said pin being movable by rotation of said operating shaft into said interlock disk notch and thereby permit operation of said operating shaft and selector gear while at the same time preventing operation of said cam shaft.

3. In a lathe including a longitudinal bed, power-driven means extending the length of said bed, and a carriage slideably supported on said bed and having an apron including mechanism for drivingly engaging said powerdriven means with said carriage; said apron mechanism comprising first and second clutch means for effectuating the driving engagement, said first and second clutch means being controlled by the rotation of operating and cam shafts, respectively, first and second cams rotatable with said cam shaft, an interlock disk rotatable with said operating shaft, each of said cams and interlock disk having a notch formed in its periphery, a pin reciprocally movable between said first cam and interlock disk, said pin having a first end portion receivable at times in said first cam notch and a second end portion receivable in said interlock disk notch when said first end portion is not received in said first cam notch, a rotatably-mounted selector gear axially movable between cooperating gear means, a plunger reciprocally movable between said selector gear and second cam, said plunger having a first end portion receivable at times 111 said second cam notch and a forked second end portion straddling said selector gear when the first end portion of said plunger is not received in said cam notch, and yieldable means biasing said plunger out of straddling engagement with said selector gear, said cams being positioned with respect to said cam shaft such that the first end portions of said pin and plunger are simultaneously received in the respective cam notches.

4. In a lathe including a longitudinal bed, first and second power-driven means extending the length of said bed, and a carriage slidably supported on said bed and having an apron including mechanism for drivingly engaging said power-driven means with said carriage; said apron mechanism comprising first and second clutch means for eifectuating the driving engagement with said first and second power-driven means, respectively, rotatablymounted operating and cam shafts, said first and second clutch means being controlled by the rotation of said operating and cam shafts, respectively, means for individually rotating said shafts, first and second cams rotatable with said cam shaft, an interlock disk rotatable with said operating shaft, each of said cams and interlock disk having a notch formed in its periphery, a pin reciprocally movable between said first cam and interlock disk, said pin having a first end portion receivable at times in said first cam notch and a second end portion receivable in said interlock disk notch when said first end portion is not received in said first cam notch, a rotatably-mounted selector gear axially movable between cooperating gear means, a plunger reciprocally movable between said selector gear and second cam, said plunger having a first end portion receivable at times in said second cam notch and a forked, second end portion straddling said selector gear when the first end portion of said plunger is not received in said second cam notch, and yieldable means biasing said plunger out of straddling engagement with said selector gear, said cams being positioned with respect to said cam shaft such that the first end portions of said pin and plunger are simultaneously received in the respective cam notches.

5. In a lathe including a longitudinal bed, a rotatablymounted lead screw and a rotatably-mounted feed rod extending the length of said bed, power means for rotating said lead screw and feed rod, and a carriage slideably supported on said bed and having an apron incluidng mechanism for drivingly engaging said lead screw and feed rod with said carriage; said apron mechanism including a half nut gripping clutch means engageable with said lead screw, a cam shaft operatively connected to said half nut gripping clutch means for controlling the driving engagement thereof with said lead screw, a feed reverse clutch means engageable with said feed rod, an operating shaft operatively connected to said feed reverse clutch means for controlling the driving enga-ngement therof with said feed rod, means for individually rotating said shafts, a selector gear operatively connected to said feed reverse clutch means for receiving rotative motion from said feed rod, said selector gear being axially movable between and engageable with cooperating gear means, first and second calms rotatable with said cam shaft, an interlock disk rotatable with said operating shaft, said cams and interlock disk each having a notch in its periphery, a pin reciprocally moveable between said first cam and interlock disk, said pin having a first end portion receivable at times in said first cam notch and a second end portion receivable in said interlock disk notch when said first end portion is not received in said first cam notch, whereby said pin maintains one of said shafts operable while the other one of said shafts is non-operable, a plunger reciprocally movable between said selector gear and second cam, said plunger having a first end portion receivable at times in said second cam notch and a forked, second end portion straddling said selector gear when the first end portion of said plunger is not received in said second cam notch, and yieldable means biasing said plunger out of straddling engagement with said selector gear, said cams being positioned on said cam shaft such that the first end portions of said pin and plunger are simultaneously received in the respective cam notches.

6. In a lathe including a longitudinal bed, a rotatably-rnounted lead screw and a rotably-mounted feed rod extending the length of said bed, power means for rotating said lead screw and feed rod, and a carriage slideably supported on said bed and having an apron including mechanism for drivingly engaging said lead screw and feed rod with said carriage; said apron mechanism comprising a half nut gripping clutch means engageable with said lead screw, a rotatably-mou-nted cam shaft operatively connected to said half nut gripping means such that the rotation of said cam shaft controls the engagement anddisengagement of said half nut gripping clutch means with said lead screw, a feed reverse clutch means engageable with said feed rod, a rotatablymounted operating shaft operatively connected to said feed reverse clutch means such that the rotation of said operating shaft controls the engagement and disengagement of said feed reverse clutch means with said feed rod, handoperated means for selectively rotating said shafts, a selector gear operatively connected to said feed reverse clutch means for receiving rotative motion from said feed rod, said selector gear being axially movable between and engageable with cooperating gear means, first and second cams secured to said cam shaft, an interlock disk secured on said operating shaft, said cams and interlock disk each having a notch in its periphery, a pin reciprocally movable between said first cam and interlock disk, said pin having a first end portion receivable at times in said first cam notch and a second end portion receivable in second cam notch when said first end portion is not received in said first cam notch, whereby said pin maintains one of said shafts operable while the other one of said shafts is non-operable, a plunger reciprocally movable between said selector gear and second cam, said plunger having a first end portion receivable at times in said second cam notch and a forked, second end portion straddling said selector gear when the first end portion of said plunger is not received in said second cam notch, and a spring biasing said plunger out of straddling engagement with said selector gear, said cams being positioned on said cam shaft such that the first end portions of said pin and plunger are simultaneously received in the respective cam notches.

7. In a lathe including a longitudinal bed, a rotatablymounted lead screw and a rotatably-mounted feed rod extending the length of said bed, power means for rotating said lead screw and feed rod, and a carriage slideably supported on said bed and having an apron including mechanism for drivingly engaging said lead screw and feed rod with said carriage; said apron mechanism comprising a half nut gripping clutch means engageable with said lead screw, a rotatably-mountedl cam shaft operatively connected to said half nut gripping means such that the rotation of said cam shaft controls the engagement and disengagement of said half nut gripping clutch means with said lead screw, a feed reverse clutch means engageable with said feed rod, a rotatably-mounted operating shaft operatively connected to said feed reverse clutch means such that the rotation of said operating shaft controls the engagement of said feed reverse clutch means with said feed rod, hand'operated means for selectively rotating said shafts, an operating gear rotatably mounted on said operating shaft and operatively to said feed reverse clutch means for receiving rotative motion from said feed rod, a selector gear engaged with said operating gear, said selector gear being axially movable between and engageable with cooperating gear means, first and second cams secured to said cam shaft, an interlock disk secured on said operating shaft, said cams and interlock disk each having a notch in its periphery, a pin reciprocally movable between said first cam and interlock disk, said pin having a first end portion receivable at times in said first cam notch and a second end portion receivable in second cam notch when said first end portion is not received in said first cam notch, whereby said pin rnaintains one of said shafts operable While the other one of said shafts is non-operable, a plunger reciprocally movable between said selector gear and second cam, said plunger having a first end portion receivable at times in said second cam notch and a forked, second end portion straddling said selector gear When the first end portion of said plunger is not received in said second cam notch, and a spring biasing said plunger out of straddling engagement with said selector gear, said cams being positioned on said carn shaft such that the first end portions of said pin and plunger are simultaneously received in the respective cam notches.

References (Iited by the Examiner UNITED STATES PATENTS Lodge et a1 Hanson Groene Bouillon Bickel FOREIGN PATENTS Great Britain. Germany.

15 WILLIAM W. DYER, JR., Primary Examiner. 

2. IN A LATHE INCLUDING A LONGITUDINAL BED, POWER-DRIVEN MEANS EXTENDING THE LENGTH OF SAID BE, AND A CARRIAGE SLIDEABLY SUPPORTED ON SAID BED AND HAVING AN APRON INCLUDING MECHANISM FOR DRIVINGLY ENGAGED SAID POWERDRIVEN MEANS WITH SAID CARRIAGE, SAID APRON MECHANISM COMPRISING FIRST AND SECOND CLUTCH MEANS FOR EFFECTUATING THE DRIVING ENGAGEMENT, SAID FIRST AND SECOND CLUTCH MEANS BEING CONTROLLED BY THE RELATION OF OPERATING AND CAM SHAFTS RESPECTIVELY, FIRST AND SECOND CAMS ROTATABLE WITH SAID CAM SHAFT, AN INTERLOCK DISK ROTATABLE WITH SAID OPERATING SHAFT, EACH OF SAID CAMS AND INTERLOCK DISK HAVING A NOTCH FORMED IN ITS PERIPHERY, A PIN RECIPROCALLY MOVABLE BETWEEN SAID FIRST CAM AND INTERLOCK DISK, SAID PIN HAVING A FIRST END PORTION RECEIVABLE AT TIMES IN SAID FIRST CAM NOTCH AND A SECOND END PORTION RECEIVABLE IN AID INTERLOCK DISK NOTCH WHEN SAID FIRST END PORTION IS NOT RECEIVED IN SAID FIRST CAM NOTCH, A ROTATABLY-MOUNTED SELECTOR GEAR AXIALLY MOVABLE BETWEEN COOPERATING GEAR MEANS, A PLUNGER RECIPROCALLY MOVABLE BETWEEN SAID SELECTOR MEANS AND SECOND CAM, SAID PLUNGER HAVING A FIRST END PORTION RECEIVABLE AT TIMES IN SAID SECOND CAM NOTCH AND A FORKED, SECOND END PORTION STRADDLING SAID SELECTOR GEAR WHEN THE FIRST END PORTION OF SAID PLUNGER IS NOT RECEIVED IN SAID SECOND CAM NOTCH, AND YIELDABLE MEANS BIASING SAID PLUNGER OUT OF STRADDLING ENGAGEMENT WITH SAID SELECTOR GEAR, SAID PIN BEING MOVABLE BY ROTATION OF SAID OPERATING SHAFT INTO SAID INTERLOCK DISK NOTCH AND THEREBY PERMIT OPERATION OF SAID OPERATING SHAFT AND SELECTOR GEAR WHILE AT THE SAME TIME PREVENTING OPERATION OF SAID CAM SHAFT. 